The diagram below shows a V16+ interposed between a ride control system and audio video playback equipment. The A/V equipment has the ability to play back hundreds of clips, and the ride control system could certainly have hundreds of buttons or sensors. The question is: how do we get the ride control system to tell the V16 what button was pushed without doing a bunch of (painful) programming in the PLC?
The simple answer is: use a strobe and binary coded bits. If a single parallel line from the PLC triggers a sequence in the V16, this sequence can easily examine the contents of other bits (in this example, seven of them) and play back audio or video based upon their configuration. Using a strobe and seven bits give you 2 to the seventh possible combinations, or 128 different commands that may be issued.
Of course, this technique can be used for more than A/V playback. Any time a large number of messages need to be sent from a simple device, it's worth considering using binary encoded bits and a strobe.